A fluxgate is a device for measuring the Earth's magnetic field and that serves to determine the orientation of the Earth's magnetic field relative to a reference axis.
When the fluxgate is mounted on an aircraft, the reference axis is aligned with the travel axis of the aircraft so that the fluxgate serves to determine the magnetic heading of the aircraft.
A fluxgate comprises two single-axis magnetometers arranged perpendicularly relative to each other in a plane that is substantially horizontal.
Each magnetometer has a core of high magnetic permeability material selected in such a manner that the Earth's magnetic field suffices to bring the core to a state close to its saturated state. The cores are surrounded by a primary winding and by a secondary winding. The primary winding is fed with alternating current (AC) so as to generate variation within the core in the magnetic field, thereby producing a potential difference across the terminals of the secondary winding. The signal that appears on the secondary winding can be processed in order to determine very accurately the components of the magnetic field in the directions of the coils concerned.
In order to subtract the vertical component of the Earth's magnetic field from the magnetometers, it is necessary to keep the magnetometers in a plane that is as horizontal as possible. For this purpose, the cores are mounted on a pendulum suspended under a plate. The windings of the magnetometers are then connected by wires to a connector that is mounted at the center of the plate.
In order to protect said wires, in particular during large swings of the pendulum, it is known to bring the wires together in order to form a twisted cable going up from the pendulum to the connector, however that nevertheless makes it necessary to have a fluxgate that is relatively heavy in order to obtain good robustness for the electrical connection without interaction on the equilibrium of the pendulum, with the fluxgate also being bulky.